A valve assembly for a fluid dispenser and a fluid dispenser comprising the same are disclosed.
Valve assemblies for viscous fluid dispensers are known from U.S. Pat. No. 6,003,731. FIGS. 16 and 19a-19d of the ""731 patent show a pumping arrangement 117) adapted to draw fluid from a package (101) and subsequently expel the fluid in accurate dosages.
However, the valve assembly disclosed in the ""731 patent is prone to clogging and therefore can be unreliable and require frequent maintenance procedures. Further, the valve assembly disclosed in the ""731 patent includes only one outlet opening or channel and therefore the dispensing apparatus of the ""731 patent can perform at only limited dispense rates.
Therefore, there is a need for an improved valve assembly for liquid dispensers which are more reliable, require less maintenance and which are capable of dispensing at slower, more accurate dispense rates and faster dispense rates.
A valve assembly for a dispenser for viscous fluids is disclosed which comprises:
a housing having at least a first opening and a second opening, and
a valve member fitted in the housing, the valve member being rotatable about an axis and comprising a first channel, extending along said axis and communicating with the first opening in the housing, and at least two outlet channels radially extending from the first channel to the circumference of the valve member;
wherein each of the radially extending outlet channels can be brought in registry with the second opening by rotating the valve member.
Thus, one of two or more outlet channels are available, rendering the valve assembly more versatile, e.g., by employing outlet channels that are mutually different, and/or more reliable, e.g., when one of the outlet channels is no longer operational as a result of fouling or clogging, another outlet opening can be used.
In an embodiment, the diameter of at least one of the radially extending outlet channels differs from that of the other channel(s). For example, one channel can have a small diameter suitable for precision dispensing, whereas the other has a (relatively) large diameter for rapidly dispensing (relatively) large amounts.
In a further preferred embodiment which is especially suitable for use in association with a buffer or pump, the housing comprises a third opening and
the valve member further comprises an inlet channel, radially extending from the circumference of the valve member to the first (axial) channel;
wherein the inlet channel can be brought in register with the third (inlet) opening by rotating the valve member.
The diameter of the second (outlet) opening in the housing may be larger than the diameter of at least some or all of the radially extending channels. In such a configuration, the fluid will be dispensed directly from the valve member, i.e., without an additional spout or nozzle, and fouling is reduced.
An apparatus for dispensing viscous fluids is also disclosed which comprises:
a turntable rotatable around an axis of rotation;
a plurality of pumps attached to and distributed around the axis of the turntable;
at least one of the pumps comprising a valve assembly according to the present invention.
The apparatus can be used, e.g., as a dispenser for several different pigments, colorants, base paints and/or additives, such as solvents or binders, which can be mixed with each other or, e.g., with a further base paint, at a point of sale.